The present invention relates to roof tiles and more particularly to such tiles which interlock when laid in side by side overlapping relationship to form a roof tile layout.
Conventional interlocking flat roof tiles have a generally rectangular shape with upper and lower surfaces, opposite side edges, top edges, and bottom edges. These tiles may be made from a variety of materials such as clay, polymer bound aggregates, and cementitious materials such as concrete. The cementitious mixture may include sand, or another aggregate, cement, coloring pigment, water, and one or more other additives to facilitate extrusion, prevent growth of fungus, etc. A variety of roof tile designs and manufacturing methods are illustrated in detail in U.S. Pat. No. 5,070,671 (Fifield et al.), U.S. Pat. No. 5,214,895 (Fifield), U.S. Pat. No. 5,490,360 (Fifield et al.), U.S. Pat. No. 5,502,940 (Fifield), and U.S. Pat. No. 5,743,059 (Fifield), the disclosures of which are incorporated herein by reference.
Interlocking roof tiles are often arranged in successive rows of roof tile elements, with the bottom edge of each row overlapping the top edge of a lower row along the roof line. The roof tile layout formed in this manner defines an effective moisture barrier and an aesthetically pleasing appearance. In an effort to improve the aesthetic appearance of such a roof tile layout, some tile installers stagger the successive roof tiles in each row by positioning alternate roof tiles lower or higher on the roof than the directly adjacent roof tiles. This approach is problematic, however, because it is difficult to align the staggered tiles properly. Further, the interlocking and overlooking edges of the roof tiles become exposed when specific tiles are lowered or raised relative to the directly adjacent tiles.
Accordingly, there is a need for a roof tile layout and a system for manufacturing roof tiles that provide for a more effective means by which a staggered roof tile layout may be created. Further, there is a need for such a system and layout that enables efficient manufacture of such roof tiles and efficient and accurate installation of such a roof tile layout.